Yes, low suited aces are definitely solid candidates (if not the best candidates) for a 4bet in this spot. That being said, I still am I pretty firm believer in having a very small 4 bet range pre ante.

Hey Jack,
Good question. I like shoving this ATos for 18bb for sure. 19-20 is super borderline, and up to 23 is fine if opener is going crazy. Sussie was pretty average opening it seemed, so I thought 21 for a shove would be +ev but not much. The issue with trapping this AT, in addition to allowing a fair price to be flatted by hands like J9s and KJos (hands we would certainly prefer to win the pot rather than flop with, even in position) is that while we may induce the occasional A-x and T-face shove, we are also bringing in some unwanted shoves from 22-66 + some shoves (KJ/KQ/JQ suited or not) that we are more positive in taking down the pot than we are getting in slightly ahead for 21bb a side.